exenatide and maleimide

Topics: Amino Acid Sequence; Animals; Blood Glucose; CHO Cells; Cricetulus; Cyclic AMP; Diabetes Mellitus, Type 2; Disease Models, Animal; Exenatide; Glucagon-Like Peptide-1 Receptor; Half-Life; Hypoglycemic Agents; Maleimides; Mice; Mice, Nude; Mice, Obese; Molecular Weight; Polyethylene Glycols

In the treatment of type 2 diabetes mellitus, it is very important to develop therapeutics with prolonged circulation half-life. Exendin-4 is a glucagon like peptide-1 receptor (GLP-1R) agonist that has been modified in different ways for imaging insulinoma and for treating type-2 diabetes. In this work, we synthesized a maleimide derivative of truncated Evans blue dye (MEB-C3-Mal) to conjugate with (Cys(40))exendin-4 to obtain a highly stable MEB-C3-(Cys(40))exendin-4 (denoted as Abextide II). Through in situ binding with endogenous albumin, Abextide II lowers blood glucose level and prolongs the hypoglycemic effect in a type 2 diabetes mouse model more than the FDA approved Albiglutide.

Topics: Animals; Chromatography, High Pressure Liquid; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Drug Stability; Evans Blue; Exenatide; Humans; Hypoglycemic Agents; Maleimides; Mice, Inbred C57BL; Naphthalenesulfonates; Peptides; Serum Albumin; Venoms

Exendin-4 (EX4), a glucagon-like peptide-1 receptor (GLP-1R) agonist that regulates blood glucose levels, has been used in the management of type-2 diabetes mellitus. EX4 can be PEGylated to improve its antidiabetic effects by enhancing its stability and extending the circulation half-life. Here, to determine whether PEGylated EX4 is effective for the treatment of sepsis, C-terminal thiol-specific PEGylated EX4s with linear maleimide-PEG-2K, -5K, -20K and trimeric maleimide-PEG-50K (hereafter referred to as EX4-2K, EX4-5K, EX4-20K, and EX4-50K, respectively) were prepared, and their antiseptic responses were investigated. These PEGylated EX4s reduced cecal ligation and puncture (CLP)-induced organ injury by decreasing hyperpermeability, and suppressing interactions between leukocytes and endothelial cells. The binding avidity and stability of EX4-50K toward GLP-1R were superior to that of wild-type EX4, as was the circulation half-life of EX4-50K. In addition, the antiseptic effects of EX4-50K were superior to those of other PEGylated EX4s, which may be attributed to enhanced proteolytic stability, longer circulation half-life, and higher receptor-binding affinity of EX4-50K due to its trimeric PEG structure. Therefore, EX4-50K may decrease CLP-induced septic mortality in vivo. There are currently neither effective preventatives against nor treatment options for sepsis; our results show that EX4-50K has the potential to treat sepsis.

Topics: Animals; Anti-Bacterial Agents; Exenatide; Human Umbilical Vein Endothelial Cells; Humans; Male; Maleimides; Mice; Mice, Inbred C57BL; Peptides; Polyethylene Glycols; Protein Binding; Protein Stability; Sepsis; Venoms

PEGylation has been a successful strategy for improving the pharmacokinetic and pharmaceutical properties of proteins and peptides. However, PEGylated products also create significant challenges for detailed structural characterization. In this work, a site-specific PEGylation strategy was successfully performed on an exendin-4 analog (Ex4C) through a maleimide method. Tricine-sodium dodecylsulfate polyacrylamide gel electrophoresis (Tricine-SDS-PAGE), analytical reversed phase HPLC (RP-HPLC) and MALDI-TOF were applied to verify the accomplishment of the PEGylation. Peptide mapping was investigated after tryptic digestion, and the PEGylaton site was successfully located on the C-terminal fragment of Ex4C. Amino acid analysis (AAA) of cysteine was then applied to verify the block in the thiol group caused by PEGylation. We believe that the combination of proper enzymatic digestion and amino acid analysis of cysteine provided an easy and convincing way to identify the PEGylation site in this maleimide method.

Topics: Amino Acid Sequence; Chemistry, Pharmaceutical; Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase; Cysteine; Electrophoresis, Polyacrylamide Gel; Exenatide; Maleimides; Molecular Sequence Data; Peptide Mapping; Peptides; Polyethylene Glycols; Protein Conformation; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Technology, Pharmaceutical; Venoms

Albumin conjugation is considered to be one of the most effective means of protracting the short in vivo lifespans of peptides and proteins. Here, we present a new long-acting antidiabetic exendin-4 conjugate linked with human serum albumin (HSA) via polyethylene glycol (PEG). As a first step toward synthesizing this conjugate, three artificial sulfhydryl groups were introduced in HSA using 2-iminothiolane at pH 8.0. This thiolated HSA was further reacted with the monomer fraction of exendin-4 (6 equiv) conjugated with maleimide-PEG(5k)-N- hydroxysuccinimide (MAL-PEG(5k)-NHS) for 3 h. Because of the presence of PEG molecules, the resulting conjugate (HSA-PEG-Ex4) was found to have a greater apparent molecular weight and a larger particle size (ca. 195 kDa and 9.48 +/- 0.74 nm) than those of HSA-exendin-4 without the PEG linker (HSA-Ex4, ca. 84.3 kDa and 7.77 +/- 0.98 nm). Although the receptor binding affinity of HSA-PEG-Ex4 on RIN-m5F cells was significantly lower than that of Ex4, its antihyperglycemic efficacy was slightly higher than that of Ex-4 and HSA-Ex4 in type 2 diabetic db/db mice. Furthermore, HSA-PEG-Ex4 had greater circulating t(1/2) and AUC(inf) values than HSA-Ex and native exendin-4 by 2.1- and 10.3-fold, respectively. Accordingly, its hypoglycemic duration was greatly increased to 31.0 h at a dose of 250 nmol/kg vs that of native Ex4 (7.0 h). Results show that the HSA-PEG-Ex4 conjugate produced has distinct advantages over HSA-Ex4 without PEG. We believe that this exendin-4 derivative, which has the merits of albumin conjugation and PEGylation, has considerable potential as a novel type 2 antidiabetic agent.

Topics: Animals; Cell Line, Tumor; Diabetes Mellitus, Experimental; Exenatide; Glucose Tolerance Test; Humans; Hypoglycemia; Hypoglycemic Agents; Male; Maleimides; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Molecular Structure; Molecular Weight; Particle Size; Peptides; Polyethylene Glycols; Rats; Serum Albumin; Succinimides; Sulfhydryl Compounds; Surface Properties; Venoms